Morchella - The Morel Mushrooms

The Morchella genus contains the species that make up the true morels. This name comes from "morchel", a word from old German meaning mushroom.

Multiple morel mushroomsThe true morels are renowned for their distinctive appearance and unique taste. Thus hunting for them (and eating them!) has grown into a sport of its own.

Yet despite their popularity, mycologists still have many questions about these mushrooms. What is the true number of species in the genus? How exactly do they feed? What conditions are needed for the mycelia to produce mushrooms?

Let's take a closer look at some of the science behind the true morels. We'll begin by looking at types of morels, then move on to reproduction and life cycle, and end with an oft debated question: mycorrhizal or saptrotrophic?


Types of Morels


So just how many species of true morels are there in the genus Morchella? If you were hoping for a straight answer I'm sorry to disappoint. The truth is that nobody knows.

Some mycologists insist there are only three species; others say there are over 50. The problem arises when we try to define what a species truly is. Do we group mushrooms by physical characteristics? DNA evidence only? What about geographical location and other traits?

As the term species is a human concept, there's bound to be disagreement over how organisms should be classified. Until we know how many species actually exist in the Morchella genus, most people divide true morels into three informal groups:

  • black morel mushroomBlack morels (right) - Known for their dark ridges when mature, although younger specimens may seem yellow. These are usually the first morels of the season to appear. They're distinguished by their caps, which are black and always attached directly to the stem.
  • Half-free morels - These appear after the blacks but before the yellows. Unlike a black or yellow, the half-free cap is attached halfway up the stem, leaving space between the bottom of the cap and the stem (like a skirt). Due to the unusual cap attachment these are more likely to be confused with the false morel, so proceed with caution.
  • Yellow morels - Known for their lighter colors. These are usually the last morels of the season to appear. They're also distinguished by their caps, which are yellow(ish) and always attached directly to the stem.

Depending on where you live, you may hear about other informal groups such as greys, whites, or reds. These vary from place to place and are often just off-colored variations of the black, half-free, or yellow.

Studies are ongoing to determine the true number of species in the genus Morchella. To read about one such study see the Morel Data Collection Project.

Return to top


Reproduction and Life Cycle


morel asciTrue morels are ascocarps, meaning they belong to the Phylum known as Ascomycota. These are the largest phylum of fungi, commonly called "sac fungi" due to their bowl-like shapes. Other types include lichens, cup fungi, truffles, and most yeasts.

Ascocarps are defined by their asci, the sex cells of the fungus that bear spores. Each ascus usually houses eight ascospores. Eight spores may not seem like a lot, but keep in mind the average morel has millions of asci!

Take a look at this wonderful picture, a close up of the asci of a black morel. Note the eight spores.

The morel life cycle is roughly as follows:

  • Spore release and germination.
  • Mycelium growth. Mycelium is made up of long, branching cells called hyphae, and is the vegetative part of a fungus.
  • Sclerotia production. A sclerotium is a hardened mass of mycelium used as a reserve in times of difficult environmental conditions. Sclerotia produce mushroom fruit bodies. Or not, depending on the conditions.
  • Mushroom (hopefully).

This is a simplified view of a precise process. Environmental conditions must be just right for the sclerotia to form mushrooms.

Return to top


You Say Saprotroph, I Say Mycorrhizal


As if Morchella science wasn't divided enough, here's one more question: How do these mushrooms feed? Are they saprotrophic or mycorrhizal?

  • Saprotrophs are scavengers, organisms that feed on the dead tissue of other beings. In the case of a mushroom, this usually means feeding on dead or dying trees.
  • Mycorrhizal fungi engage in symbiotic relationships with the roots of plants. Fungi gain access to more carbohydrates through plant photosynthesis, and plants gain better access to water and nutrients.

The evidence for morels as mycorrhizal fungi is strong. As they're often found near certain types of trees such as elm and apple, mycologists believe they form relationships with the roots of these trees. They are also notoriously difficult to impossible to cultivate in a lab.

However, they also display saprotrophic qualities. The trees they're found near are often dead or dying, and their mycelium colonizes dead organic material quickly.

More research is needed before the true Morchella place in nature is revealed. It is now widely accepted that morels can play the role of both saprotroph and mycorrhizal partner.

So many different variables come together to create the mysterious morel! As science and amateur observation moves forward, so will our understanding of this prized mushroom.

Return to top


The picture of morel asci was taken by Peter G. Werner and is published on Wikipedia under the GNU Free Documentation License.